Method for Reducing Zearalenone Content in Straw Using Steam Explosion Technology and Use Thereof

ABSTRACT

The present disclosure provides a method for reducing zearalenone content in straw using steam explosion technology and use thereof, creatively utilizes the huge energy released during steam explosion, and destroys the chemical structure of zearalenone without introducing other harmful chemicals, wherein the steam explosion technology can be used as a completely new technology for reducing zearalenone content in straw.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of and takes priority from ChinesePatent Application Ser. No. 201810247485.2 filed on Mar. 23, 2018, thecontents of which are herein incorporated by reference.

TECHNICAL FIELD

The present disclosure belongs to the technical field of livestock feedprocessing, and specifically relates to a method for reducingzearalenone content in straw using steam explosion technology and usethereof.

BACKGROUND

The limit test of fungal toxin residues is a key test and monitoringitem for agricultural product safety in China, and is also one of thenecessary test items for many agricultural and sideline products toenter the international market. The fungal toxins are toxic secondarymetabolites secreted by fungi. The fungal toxins contaminate food andfeed, thereby resulting in food spoilage, and poisoning humans andanimals. As the countries around the world increasingly pay attention tothe management of fungal toxin residues in food and feed, it appearsparticularly important to reduce the food and feed contamination causedby the fungal toxins, in order to reduce the damage of the fungal toxinsto humans and animals.

Zearalenone is also known as F-2 toxin, has a chemical name of6-(10-hydroxy-6-oxo-trans-1-undecene)-β-resorcyclic acid-lactone, is oneof the most widely distributed fusarium mycotoxins, and is mainlyderived from strains of Fusarium, such as Fusariumtricinctum andFusarium graminearum. Zearalenone mainly contaminates cereals, such asmaize, wheat, rice, barley, millet, and oats, and has estrogen-likeeffects, such as reproductive developmental toxicity, immunotoxicity andgenotoxicity, and accelerates the formation of tumors. Intake ofexcessive zearalenone by animals will cause acute poisoning, or evendeath, thereby resulting in huge economic losses to livestock farms.

Zearalenone is commonly found in moldy straw, especially in maize straw.However, at present, there are no particularly effective methods forreducing the zearalenone content in straw. The traditional physical andchemical methods have the defects, such as poor effects, and tend tointroduce other harmful chemicals.

SUMMARY

In order to solve the above problems existing in the prior art, thepresent disclosure provides a method for reducing zearalenone content instraw using steam explosion technology and use thereof.

The present disclosure discloses use of the steam explosion technologyfor reducing zearalenone content in straw.

The steam explosion technology has a long history since it was proposedand used. Its main working principle is to swell up starting materialsby steam in an environment at high temperature and under high pressure,fill pores with steam, rapidly gasify overheated liquid in pores of thestarting materials when the high pressure is instantaneously removed(millisecond level, within 0.00875 second), enable the cells to“explode” due to rapid volume expansion, form porous cell walls afterthe cell wall rupture, and release micromolecular substances from withinthe cells. The steam explosion technology can cause occurrence of avariety of chemical and physical changes of materials only using hightemperature steam in processing works without adding any chemicalsubstance, and is therefore considered as the processing approach withbest development prospects.

Before the present disclosure, the steam explosion technology improvesthe crystallinity of cellulose in starting materials, reduces thepolymerization degree, softens the lignin, and reduces the horizontalbonding strength. The inventors of the disclosure has found throughresearch on the principle of the steam explosion that the chemicalstructure of zearalenone can be destroyed using the huge energy releasedduring steam explosion without introducing other harmful chemicals, andthe steam explosion technology can be used as a completely newtechnology for reducing zearalenone content in straw.

The technical solution used by the present disclosure is a method forreducing zearalenone content in straw using steam explosion technology,wherein straw is processed using a steam explosion method with 1-2.2 MPaof steam pressure of steam explosion, 30-200 s of pressure maintainingtime, and 10-50% water content of straw.

The inventors of the present disclosure further select parameters of thesteam explosion technology to give straw containing zearalenone at alower concentration after processing. Tests show that it is possible tobetter meet the requirements for reducing zearalenone content using theabove parameters.

In another aspect, the steam explosion technology can further pulverizestraw whilst destroying zearalenone content in straw, and has greaterefficiency in subsequent use of straw as feeds or fermentationmaterials.

In the present disclosure, the degradation rate of zearalenone is usedto evaluate the removal effect of zearalenone, and the theoreticalmaximum gas yield is used to evaluate the efficiency of steam explodedstraw.

According to an example of the present disclosure, the steam pressure ofsteam explosion is 2.2 MPa, the pressure maintaining time is 144 s, andthe water content of straw is 10%. Under the conditions, the maximumdegradation rate of zearalenone is achieved.

According to an example of the present disclosure, the steam pressure ofsteam explosion is 1.48 MPa, the pressure maintaining time is 30 s, andthe water content of straw is 50%. Under the conditions, the processedstraw has a highest theoretical maximum gas yield.

According to an example of the present disclosure, the steam pressure ofsteam explosion is 1.88 MPa, the pressure maintaining time is 105.91 s,and the water content of straw is 50%. Under the conditions, theintegrated value of the degradation rate of zearalenone and thetheoretical maximum gas yield is the optimal combination.

In order to smoothly perform steam explosion, a preferable technicalsolution is that, before steam explosion, the method further comprises apre-processing step: drying moldy maize straw at 65° C. for 72 hr or toconstant weight, pulverizing to straw particles with a particle size of2-10 mm, spraying water on the pulverized straw particles based on thewater content, and sealing for use.

In order to facilitate verification and adjustment of the steamexplosion technology, the present disclosure further comprises, aftersteam explosion, a step of detecting the degradation rate of zearalenoneby HPLC; and further comprises, after steam explosion, a step ofdetecting the theoretical maximum gas yield of straw by in vitroaerogenesis method.

It should be noted that an example of the present disclosure provides amethod for detecting the degradation rate of zearalenone by HPLC and amethod for detecting the theoretical maximum gas yield by in vitroaerogenesis method. Based on the actual test and production conditions,those skilled in the art can select other detection methods anddetection parameters, which are not repeated any more herein.

The present disclosure has following beneficial effects:

1. The present disclosure provides a method for reducing zearalenonecontent in straw using steam explosion technology and use thereof,creatively utilizes the huge energy released during steam explosion, anddestroys the chemical structure of zearalenone without introducing otherharmful chemicals, wherein the steam explosion technology can be used asa completely new technology for reducing zearalenone content in straw.

2. The inventors of the present disclosure further select parameters ofthe steam explosion technology to give straw containing zearalenone at alower concentration after processing, and to obtain good implementationparameters and optimum implementation parameters of steam explosion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a response surface analysis diagram of a degradation rate ofzearalenone in exploded straw at water contents of different levels andunder different steam pressure conditions; wherein degradation rate ofZEN (%) represents the degradation rate of zearalenone, water (%)represents the water content, and pressure (mPa) represents the steampressure (mPa);

FIG. 2 is a response surface analysis diagram of a degradation rate ofzearalenone in exploded straw in pressure maintaining time of differentlevels and under different steam pressure conditions; whereindegradation rate of ZEN (%) represents the degradation rate ofzearalenone, time (s) represents the pressure maintaining time, andpressure (mPa) represents the steam pressure (mPa); and

FIG. 3 is a response surface analysis diagram of a theoretical maximumgas yield of exploded straw in pressure maintaining time of differentlevels and under different steam pressure conditions; wherein A (mL/g)represents the theoretical maximum gas yield, time (s) represents thepressure maintaining time, and pressure (mPa) represents the steampressure (mPa).

DETAILED DESCRIPTION OF EMBODIMENTS

The content of the present disclosure is illustrated in more detailhereinafter in conjunction with the following examples. It should beunderstood that the implementation of the disclosure is not limited tothe following examples, and any form of modifications and/or changes ofthe disclosure will fall within the scope of protection of thedisclosure.

In the present disclosure, unless otherwise particularly specified, allparts and percentages are referred to by weight, and all devices andstarting materials can be commercially available or are commonly used inthe industry. All methods in the following examples, unless otherwiseindicated, are conventional methods in the field.

The inventors of the present disclosure give the response surfaceanalysis diagrams of FIG. 1-3 based on a series of test parameters. Thedisclosure is illustrated in conjunction with the following examples.

EXAMPLE 1

A method for reducing zearalenone content in straw using steam explosiontechnology comprises the following steps:

A: Pre-processing: drying 50 g of moldy maize straw at 65° C. for 72 hror to constant weight, pulverizing to straw particles with a particlesize of 2-10 mm, spraying water on the pulverized straw particles basedon the water content, packing and sealing in a plastic bag, and storingat room temperature for about 24 hr;

B: Steam explosion: processing straw particles using a steam explosionmethod, wherein the steam pressure of steam explosion was 1 MPa, thepressure maintaining time was 200 s, and the water content of strawparticles was 10%; and

C: Collecting steam exploded straw particles in a conical flask, dryingat 65° C. for 72 hr or to constant weight, and storing for lateranalysis, including detecting the degradation rate of zearalenone byHPLC and detecting the theoretical maximum gas yield of straw by invitro aerogenesis method.

The method for detecting the degradation rate of zearalenone by HPLCwas: 1 g of processed straw was transferred into a 50 mL centrifugetube, followed by addition of 8 mL of acetonitrile-water-formic acid(v/v, 84:16:0.1) solution, fully mixing on a shaker for 10 min,ultrasonic oscillation for 30 min, centrifugation at 10,000 rpm for 5min, and collecting the filtrate. 8 mL of the filtrate was filteredthrough Mycosep226 multifunctional purification column to give apurified liquid. 200 μL of the purified liquid was pipetted to a brownglass bottle with a stopper, and tested on a machine. The quantitativedetection conditions were: the mobile phase was acetonitrile-water (v/v,25:75) solution, the flow rate was set as 0.5 mL/min, the columntemperature was 30° C., the sample injection was 25 μL; and thedetection parameters of the fluorescence detector were set at excitationwavelength of 360 nm and emission wavelength of 440 nm. Finally, theconcentration of zearalenone in unexploded moldy straw and that inexploded straw extract (purified liquid) were obtained respectively,ng/mL. The concentration was multiplied by the volume (8 mL) of theextract, to give the zearalenone content in 1 g of sample, ng. Theresult obtained by subtracting the zearalenone content in exploded strawfrom the zearalenone content in unexploded moldy straw was divided bythe zearalenone content in unexploded moldy straw, and the degradationrate of zearalenone in exploded moldy straw was finally obtained.

The method for detecting the theoretical maximum gas yield of straw byin vitro aerogenesis method was as follows: 0.3 g of steam explodedstraw was added into 100 mL of a fermentator, and anaerobicallyincubated at constant temperature together with 45 mL of anaerobicfermentation broth (volume ratio of rumen liquid to buffer solution was1:2) at 39° C. for 72 hr, and the pressure in the fermentator wasdetermined using a pressure gauge in 0, 2, 4, 8, 12, 18, 24, 36, 48 and72 hr.

According to the formula GPt=Pt×V/(100.3×w) (GPt is the cumulative gasyield at timepoint t, Pt is the pressure in each fermentator at timepoint t, V is the volume of residual fermentation broth in thefermentator, 100.3 is the atmospheric pressure, and w is the straw massin each fermentator), the cumulative gas yield in the each fermentatorat different timepoints was obtained, mL/g. By referring to theexponential function model GPt=[1-e-c×(t−lag)]×A (GPt is the cumulativegas yield at timepoint t, c is the gas generation rate, t is the gasgeneration time, lag is the gas generation lag time, and A is thetheoretical maximum gas yield of the fermentation substrate at the gasgeneration rate) proposed by rskov et al., the theoretical maximum gasyield of the fermentation substrate at the gas generation rate wasfinally obtained through nonlinear fitting of the cumulative gas yielddata, mL/g.

In this example, the degradation rate of zearalenone in steam explodedstraw was 67.41%, and the theoretical maximum gas yield was 239.09 mL/g.

EXAMPLE 2

A method for reducing zearalenone content in straw using steam explosiontechnology comprises the following steps:

A: Pre-processing: drying 50 g of moldy maize straw at 65° C. for 72 hror to constant weight, pulverizing to straw particles with a particlesize of 2-10 mm, spraying water on the pulverized straw particles basedon the water content, packing and sealing in a plastic bag, and storingat room temperature for about 24 hr;

B: Steam explosion: processing straw particles using a steam explosionmethod, wherein the steam pressure of steam explosion was 2.2 MPa, thepressure maintaining time was 30 s, and the water content of strawparticles was 50%; and

C: Collecting steam exploded straw particles in a conical flask, dryingat 65° C. for 72 hr or to constant weight, and storing for lateranalysis, including detecting the degradation rate of zearalenone byHPLC and detecting the theoretical maximum gas yield of straw by invitro aerogenesis method.

The method for detecting the degradation rate of zearalenone by HPLCwas: 1 g of processed straw was transferred into a 50 mL centrifugetube, followed by addition of 8 mL of acetonitrile-water-formic acid(v/v, 84:16:0.1) solution, fully mixing on a shaker for 10 min,ultrasonic oscillation for 30 min, centrifugation at 10,000 rpm for 5min, and collecting the filtrate. 8 mL of the filtrate was filteredthrough Mycosep226 multifunctional purification column to give apurified liquid. 200 μL of the purified liquid was pipetted to a brownglass bottle with a stopper, and tested on a machine. The quantitativedetection conditions were: the mobile phase was acetonitrile-water (v/v,25:75) solution, the flow rate was set as 0.5 mL/min, the columntemperature was 30° C., the sample injection was 25 μL; and thedetection parameters of the fluorescence detector were set at excitationwavelength of 360 nm and emission wavelength of 440 nm. Finally, theconcentration of zearalenone in unexploded moldy straw and that inexploded straw extract (purified liquid) were obtained respectively,ng/mL. The concentration was multiplied by the volume (8 mL) of theextract, to give the zearalenone content in 1 g of sample, ng. Theresult obtained by subtracting the zearalenone content in exploded strawfrom the zearalenone content in unexploded moldy straw was divided bythe zearalenone content in unexploded moldy straw, and the degradationrate of zearalenone in exploded moldy straw was finally obtained.

The method for detecting the theoretical maximum gas yield of straw byin vitro aerogenesis method was as follows: 0.3 g of steam explodedstraw was added into 100 mL of a fermentator, and anaerobicallyincubated at constant temperature together with 45 mL of anaerobicfermentation broth (volume ratio of rumen liquid to buffer solution was1:2) at 39° C. for 72 hr, and the pressure in the fermentator wasdetermined using a pressure gauge in 0, 2, 4, 8, 12, 18, 24, 36, 48 and72 hr. According to the formula GPt=Pt×V/(100.3×w) (GPt is thecumulative gas yield at timepoint t, Pt is the pressure in eachfermentator at time point t, V is the volume of residual fermentationbroth in the fermentator, 100.3 is the atmospheric pressure, and w isthe straw mass in each fermentator), the cumulative gas yield in theeach fermentator at different timepoints was obtained, mL/g. Byreferring to the exponential function model GPt=[1-e-c×(t−lag)]×A (GPtis the cumulative gas yield at timepoint t, c is the gas generationrate, t is the gas generation time, lag is the gas generation lag time,and A is the theoretical maximum gas yield of the fermentation substrateat the gas generation rate) proposed by rskov et al., the theoreticalmaximum gas yield of the fermentation substrate at the gas generationrate was finally obtained through nonlinear fitting of the cumulativegas yield data, mL/g.

In this example, the degradation rate of zearalenone in steam explodedstraw was 72.18%, and the theoretical maximum gas yield was 240.71 mL/g.

EXAMPLE 3

A method for reducing zearalenone content in straw using steam explosiontechnology comprises the following steps:

A: Pre-processing: drying 50 g of moldy maize straw at 65° C. for 72 hror to constant weight, pulverizing to straw particles with a particlesize of 2-10 mm, spraying water on the pulverized straw particles basedon the water content, packing and sealing in a plastic bag, and storingat room temperature for about 24 hr;

B: Steam explosion: processing straw particles using a steam explosionmethod, wherein the steam pressure of steam explosion was 1.6 MPa, thepressure maintaining time was 115 s, and the water content of strawparticles was 30%; and

C: Collecting steam exploded straw particles in a conical flask, dryingat 65° C. for 72 hr or to constant weight, and storing for lateranalysis, including detecting the degradation rate of zearalenone byHPLC and detecting the theoretical maximum gas yield of straw by invitro aerogenesis method.

The method for detecting the degradation rate of zearalenone by HPLCwas: 1 g of processed straw was transferred into a 50 mL centrifugetube, followed by addition of 8 mL of acetonitrile-water-formic acid(v/v, 84:16:0.1) solution, fully mixing on a shaker for 10 min,ultrasonic oscillation for 30 min, centrifugation at 10,000 rpm for 5min, and collecting the filtrate. 8 mL of the filtrate was filteredthrough Mycosep226 multifunctional purification column to give apurified liquid. 200 μL of the purified liquid was pipetted to a brownglass bottle with a stopper, and tested on a machine. The quantitativedetection conditions were: the mobile phase was acetonitrile-water (v/v,25:75) solution, the flow rate was set as 0.5 mL/min, the columntemperature was 30° C., the sample injection was 25 μL; and thedetection parameters of the fluorescence detector were set at excitationwavelength of 360 nm and emission wavelength of 440 nm. Finally, theconcentration of zearalenone in unexploded moldy straw and that inexploded straw extract (purified liquid) were obtained respectively,ng/mL. The concentration was multiplied by the volume (8 mL) of theextract, to give the zearalenone content in 1 g of sample, ng. Theresult obtained by subtracting the zearalenone content in exploded strawfrom the zearalenone content in unexploded moldy straw was divided bythe zearalenone content in unexploded moldy straw, and the degradationrate of zearalenone in exploded moldy straw was finally obtained.

The method for detecting the theoretical maximum gas yield of straw byin vitro aerogenesis method was as follows: 0.3 g of steam explodedstraw was added into 100 mL of a fermentator, and anaerobicallyincubated at constant temperature together with 45 mL of anaerobicfermentation broth (volume ratio of rumen liquid to buffer solution was1:2) at 39° C. for 72 hr, and the pressure in the fermentator wasdetermined using a pressure gauge in 0, 2, 4, 8, 12, 18, 24, 36, 48 and72 hr. According to the formula GPt=Pt×V/(100.3×w) (GPt is thecumulative gas yield at timepoint t, Pt is the pressure in eachfermentator at time point t, V is the volume of residual fermentationbroth in the fermentator, 100.3 is the atmospheric pressure, and w isthe straw mass in each fermentator), the cumulative gas yield in theeach fermentator at different timepoints was obtained, mL/g. Byreferring to the exponential function model GPt=[1-e-c×(t−lag)]×A (GPtis the cumulative gas yield at timepoint t, c is the gas generationrate, t is the gas generation time, lag is the gas generation lag time,and A is the theoretical maximum gas yield of the fermentation substrateat the gas generation rate) proposed by rskov et al., the theoreticalmaximum gas yield of the fermentation substrate at the gas generationrate was finally obtained through nonlinear fitting of the cumulativegas yield data, mL/g.

In this example, the degradation rate of zearalenone in steam explodedstraw was 63.63%, and the theoretical maximum gas yield was 263.61 mL/g.

EXAMPLE 4

A method for reducing zearalenone content in straw using steam explosiontechnology comprises the following steps:

A: Pre-processing: drying 50 g of moldy maize straw at 65° C. for 72 hror to constant weight, pulverizing to straw particles with a particlesize of 2-10 mm, spraying water on the pulverized straw particles basedon the water content, packing and sealing in a plastic bag, and storingat room temperature for about 24 hr;

B: Steam explosion: processing straw particles using a steam explosionmethod, wherein the steam pressure of steam explosion was 2.2 MPa, thepressure maintaining time was 144 s, and the water content of straw was10%; and

C: Collecting steam exploded straw particles in a conical flask, dryingat 65° C. for 72 hr or to constant weight, and storing for lateranalysis, including detecting the degradation rate of zearalenone byHPLC and detecting the theoretical maximum gas yield of straw by invitro aerogenesis method.

The method for detecting the degradation rate of zearalenone by HPLCwas: 1 g of processed straw was transferred into a 50 mL centrifugetube, followed by addition of 8 mL of acetonitrile-water-formic acid(v/v, 84:16:0.1) solution, fully mixing on a shaker for 10 min,ultrasonic oscillation for 30 min, centrifugation at 10,000 rpm for 5min, and collecting the filtrate. 8 mL of the filtrate was filteredthrough Mycosep226 multifunctional purification column to give apurified liquid. 200 μL of the purified liquid was pipetted to a brownglass bottle with a stopper, and tested on a machine. The quantitativedetection conditions were: the mobile phase was acetonitrile-water (v/v,25:75) solution, the flow rate was set as 0.5 mL/min, the columntemperature was 30 ° C., the sample injection was 25 μL; and thedetection parameters of the fluorescence detector were set at excitationwavelength of 360 nm and emission wavelength of 440 nm. Finally, theconcentration of zearalenone in unexploded moldy straw and that inexploded straw extract (purified liquid) were obtained respectively,ng/mL. The concentration was multiplied by the volume (8 mL) of theextract, to give the zearalenone content in 1 g of sample, ng. Theresult obtained by subtracting the zearalenone content in exploded strawfrom the zearalenone content in unexploded moldy straw was divided bythe zearalenone content in unexploded moldy straw, and the degradationrate of zearalenone in exploded moldy straw was finally obtained.

The method for detecting the theoretical maximum gas yield of straw byin vitro aerogenesis method was as follows: 0.3 g of steam explodedstraw was added into 100 mL of a fermentator, and anaerobicallyincubated at constant temperature together with 45 mL of anaerobicfermentation broth (volume ratio of rumen liquid to buffer solution was1:2) at 39° C. for 72 hr, and the pressure in the fermentator wasdetermined using a pressure gauge in 0, 2, 4, 8, 12, 18, 24, 36, 48 and72 hr. According to the formula GPt=Pt×V/(100.3×w) (GPt is thecumulative gas yield at timepoint t, Pt is the pressure in eachfermentator at time point t, V is the volume of residual fermentationbroth in the fermentator, 100.3 is the atmospheric pressure, and w isthe straw mass in each fermentator), the cumulative gas yield in theeach fermentator at different timepoints was obtained, mL/g. Byreferring to the exponential function model GPt=[1-e-c×(t−lag)]×A (GPtis the cumulative gas yield at timepoint t, c is the gas generationrate, t is the gas generation time, lag is the gas generation lag time,and A is the theoretical maximum gas yield of the fermentation substrateat the gas generation rate) proposed by rskov et al., the theoreticalmaximum gas yield of the fermentation substrate at the gas generationrate was finally obtained through nonlinear fitting of the cumulativegas yield data, mL/g.

In this example, the degradation rate of zearalenone in steam explodedstraw was 83%, and the theoretical maximum gas yield was 224.46 mL/g.Under the conditions, the maximum degradation rate of zearalenone wasachieved.

EXAMPLE 5

A method for reducing zearalenone content in straw using steam explosiontechnology comprises the following steps:

A: Pre-processing: drying 50 g of moldy maize straw at 65° C. for 72 hror to constant weight, pulverizing to straw particles with a particlesize of 2-10 mm, spraying water on the pulverized straw particles basedon the water content, packing and sealing in a plastic bag, and storingat room temperature for about 24 hr;

B: Steam explosion: processing straw particles using a steam explosionmethod, wherein the steam pressure of steam explosion was 1.48 MPa, thepressure maintaining time was 30 s, and the water content of strawparticles was 50%; and

C: Collecting steam exploded straw particles in a conical flask, dryingat 65° C. for 72 hr or to constant weight, and storing for lateranalysis, including detecting the degradation rate of zearalenone byHPLC and detecting the theoretical maximum gas yield of straw by invitro aerogenesis method.

The method for detecting the degradation rate of zearalenone by HPLCwas: 1 g of processed straw was transferred into a 50 mL centrifugetube, followed by addition of 8 mL of acetonitrile-water-formic acid(v/v, 84:16:0.1) solution, fully mixing on a shaker for 10 min,ultrasonic oscillation for 30 min, centrifugation at 10,000 rpm for 5min, and collecting the filtrate. 8 mL of the filtrate was filteredthrough Mycosep226 multifunctional purification column to give apurified liquid. 200 μL of the purified liquid was pipetted to a brownglass bottle with a stopper, and tested on a machine. The quantitativedetection conditions were: the mobile phase was acetonitrile-water (v/v,25:75) solution, the flow rate was set as 0.5 mL/min, the columntemperature was 30 ° C., the sample injection was 25 μL; and thedetection parameters of the fluorescence detector were set at excitationwavelength of 360 nm and emission wavelength of 440 nm. Finally, theconcentration of zearalenone in unexploded moldy straw and that inexploded straw extract (purified liquid) were obtained respectively,ng/mL. The concentration was multiplied by the volume (8 mL) of theextract, to give the zearalenone content in 1 g of sample, ng. Theresult obtained by subtracting the zearalenone content in exploded strawfrom the zearalenone content in unexploded moldy straw was divided bythe zearalenone content in unexploded moldy straw, and the degradationrate of zearalenone in exploded moldy straw was finally obtained.

The method for detecting the theoretical maximum gas yield of straw byin vitro aerogenesis method was as follows: 0.3 g of steam explodedstraw was added into 100 mL of a fermentator, and anaerobicallyincubated at constant temperature together with 45 mL of anaerobicfermentation broth (volume ratio of rumen liquid to buffer solution was1:2) at 39° C. for 72 hr, and the pressure in the fermentator wasdetermined using a pressure gauge in 0, 2, 4, 8, 12, 18, 24, 36, 48 and72 hr. According to the formula GPt=Pt×V/(100.3×w) (GPt is thecumulative gas yield at timepoint t, Pt is the pressure in eachfermentator at time point t, V is the volume of residual fermentationbroth in the fermentator, 100.3 is the atmospheric pressure, and w isthe straw mass in each fermentator), the cumulative gas yield in theeach fermentator at different timepoints was obtained, mL/g. Byreferring to the exponential function model GPt=[1-e-c×(t−lag)]×A (GPtis the cumulative gas yield at timepoint t, c is the gas generationrate, t is the gas generation time, lag is the gas generation lag time,and A is the theoretical maximum gas yield of the fermentation substrateat the gas generation rate) proposed by rskov et al., the theoreticalmaximum gas yield of the fermentation substrate at the gas generationrate was finally obtained through nonlinear fitting of the cumulativegas yield data, mL/g.

In this example, the degradation rate of zearalenone in steam explodedstraw was 53.18%, and the theoretical maximum gas yield was 245.61 mL/gUnder the conditions, the processed straw had the highest theoreticalmaximum gas yield.

EXAMPLE 6

A method for reducing zearalenone content in straw using steam explosiontechnology comprises the following steps:

A: Pre-processing: drying 50 g of moldy maize straw at 65° C. for 72 hror to constant weight, pulverizing to straw particles with a particlesize of 2-10 mm, spraying water on the pulverized straw particles basedon the water content, packing and sealing in a plastic bag, and storingat room temperature for about 24 hr;

B: Steam explosion: processing straw particles using a steam explosionmethod, wherein the steam pressure of steam explosion was 1.88 MPa, thepressure maintaining time was 105.91 s, and the water content of strawwas 50%; and

C: Collecting steam exploded straw particles in a conical flask, dryingat 65° C. for 72 hr or to constant weight, and storing for lateranalysis, including detecting the degradation rate of zearalenone byHPLC and detecting the theoretical maximum gas yield of straw by invitro aerogenesis method.

The method for detecting the degradation rate of zearalenone by HPLCwas: 1 g of processed straw was transferred into a 50 mL centrifugetube, followed by addition of 8 mL of acetonitrile-water-formic acid(v/v, 84:16:0.1) solution, fully mixing on a shaker for 10 min,ultrasonic oscillation for 30 min, centrifugation at 10,000 rpm for 5min, and collecting the filtrate. 8 mL of the filtrate was filteredthrough Mycosep226 multifunctional purification column to give apurified liquid. 200 μL of the purified liquid was pipetted to a brownglass bottle with a stopper, and tested on a machine. The quantitativedetection conditions were: the mobile phase was acetonitrile-water (v/v,25:75) solution, the flow rate was set as 0.5 mL/min, the columntemperature was 30° C., the sample injection was 25 μL; and thedetection parameters of the fluorescence detector were set at excitationwavelength of 360 nm and emission wavelength of 440 nm. Finally, theconcentration of zearalenone in unexploded moldy straw and that inexploded straw extract (purified liquid) were obtained respectively,ng/mL. The concentration was multiplied by the volume (8 mL) of theextract, to give the zearalenone content in 1 g of sample, ng. Theresult obtained by subtracting the zearalenone content in exploded strawfrom the zearalenone content in unexploded moldy straw was divided bythe zearalenone content in unexploded moldy straw, and the degradationrate of zearalenone in exploded moldy straw was finally obtained.

The method for detecting the theoretical maximum gas yield of straw byin vitro aerogenesis method was as follows: 0.3 g of steam explodedstraw was added into 100 mL of a fermentator, and anaerobicallyincubated at constant temperature together with 45 mL of anaerobicfermentation broth (volume ratio of rumen liquid to buffer solution was1:2) at 39° C. for 72 hr, and the pressure in the fermentator wasdetermined using a pressure gauge in 0, 2, 4, 8, 12, 18, 24, 36, 48 and72 hr. According to the formula GPt=Pt×V/(100.3×w) (GPt is thecumulative gas yield at timepoint t, Pt is the pressure in eachfermentator at time point t, V is the volume of residual fermentationbroth in the fermentator, 100.3 is the atmospheric pressure, and w isthe straw mass in each fermentator), the cumulative gas yield in theeach fermentator at different timepoints was obtained, mL/g. Byreferring to the exponential function model GPt=[1-e-c×(t−lag)]×A (GPtis the cumulative gas yield at timepoint t, c is the gas generationrate, t is the gas generation time, lag is the gas generation lag time,and A is the theoretical maximum gas yield of the fermentation substrateat the gas generation rate) proposed by rskov et al., the theoreticalmaximum gas yield of the fermentation substrate at the gas generationrate was finally obtained through nonlinear fitting of the cumulativegas yield data, mL/g.

In this example, the degradation rate of zearalenone in steam explodedstraw was 71.31%, and the theoretical maximum gas yield was 242.11 mL/g.Under the conditions, the maximum degradation rate of zearalenone wasachieved.

Finally, it should be noted that the above examples are only used toillustrate, rather than to limit, the technical solution of the presentdisclosure. While the disclosure is illustrated in detail with referenceto preferred examples, it should be understood that the foregoingdescription is only embodiments of the disclosure, and is not used tolimit the scope of protection of the disclosure. Any modification,equivalent replacement, improvement, or the like made within the spiritand principle of the disclosure should be included within the scope ofprotection of the disclosure.

What is claimed is:
 1. Use of steam explosion technology for reducingzearalenone content in straw.
 2. A method for reducing zearalenonecontent in straw using steam explosion technology, wherein straw isprocessed using a steam explosion method with 1-2.2 MPa of steampressure of steam explosion, 30-200 s of pressure maintaining time, and10-50% water content of straw.
 3. The method according to claim 2,wherein the steam pressure of steam explosion is 2.2 MPa, the pressuremaintaining time is 144 s, and the water content of straw is 10%.
 4. Themethod according to claim 2, wherein the steam pressure of steamexplosion is 1.48 MPa, the pressure maintaining time is 30 s, and thewater content of straw is 50%.
 5. The method according to claim 2,wherein the steam pressure of steam explosion is 1.88 MPa, the pressuremaintaining time is 105.91 s, and the water content of straw is 50%. 6.The method according to claim 2, further comprising, before steamexplosion, a pre-processing step: drying moldy maize straw at 65° C. for72 hr or to constant weight, pulverizing to straw particles with aparticle size of 2-10 mm, spraying water on the pulverized strawparticles based on the water content, and sealing for use.
 7. The methodaccording to claim 2, further comprising, after steam explosion, a stepof detecting a degradation rate of zearalenone by HPLC.
 8. The methodaccording to claim 2, further comprising, after steam explosion, a stepof detecting a theoretical maximum gas yield of straw by in vitroaerogenesis method.